Stereotactic surgery, or stereotaxy, is a minimally invasive form of surgical intervention which makes use of a three-dimensional coordinate system to locate small targets inside the body and to perform on them some action such as ablation, biopsy, lesion, injection, stimulation, implantation or radiosurgery (SRS).
Neurosurgeries are usually conducted under general anaesthesia, but in some cases the patient is awaken during surgery to perform live tests that guide the surgeon during the operation. This is for instance becoming a routine procedure during the implantation of Deep-Brain Stimulators (DBS) for the treatment of essential tremor (ET) and Parkinson Disease (PD). In this procedure, one or more electrodes are placed in deep structures of the brain according to a preliminary localization performed with brain imaging. However, a final check is performed during the surgery to fine-tune the electrode placement and avoid having to re-operate, a practice which is generally called Intraoperative Brain Mapping. In brief, the patient is awakened for a few minutes and the surgery team monitors the tremors on the arm of the patient that become visible as soon as he is awakened: switching the stimulator on should immediately stop the tremors. Being able to adjust the location of the electrode while observing the direct effect on the tremors has the strong advantage of allowing the most appropriate placement and to ensure a successful operation. The same principle applies for ablation and radiosurgery in order to ensure that critical brain areas for important functions are not damaged, for example motor or speech.
Considering the success of DBS on motor disorders, with over 100 000 patients implanted worldwide in 2013, and based on neurological insight of brain functions, it is currently investigated to apply DBS on patients suffering from cognitive disorders such as depression, Obsessive Compulsive Disorders (OCD), Tourette Syndrome or obesity, as examples among the nineteen (19) disorders currently being studied. In these cases, the neurosurgeon cannot rely on a motor feedback (suppression of motor tremors) to ensure the successful placement and efficacy of implanted electrodes. The examination shall here be cognitive and behavioural and is harder to test, thus it is not currently performed during surgery.
Virtual reality (VR) technologies are known for their ability to test cognition, mood, impulsivity, reaction to stimuli and behaviour, in an ecologically valid simulation context adapted to various neurological conditions. VR can therefore provide the cognitive and behavioural simulations required for some new and future use of stereotactic neurosurgery for high level brain functions. VR could for instance be used to guide the placement of neuro-stimulation electrodes during DBS implantation for cognitive and affective disorders.
What remains to be done is to bring VR simulation for patients inside the operating room during awake stereotactic neurosurgery. In particular, head mounted displays to immerse patients lying on the operating table are not available as of today. Accordingly, in light of these deficiencies of the background art, additional and more sophisticated solutions, devices, and methods for VR for surgical procedures are strongly desired.